IBIC2019 - Classification: Machine measurements and novel techniques

Paper	Title	Page
MOCO03	Estimation of Longitudinal Profiles of Ion Bunches in the LHC Using Schottky-Based Diagnostics	45
	K. Łasocha, D. Alves CERN, Meyrin, Switzerland
	The Large Hadron Collider (LHC) Schottky monitors have been designed to measure various parameters of relevance to beam quality, namely tune, momentum spread and chromaticity. We present another application of this instrument - the evaluation of longitudinal bunch profiles. The relation between the distribution of synchrotron amplitudes within the bunch population and the longitudinal bunch profile is derived from probabilistic principles. Our approach, limited to bunched beams with no intra-bunch coherent motion, initially fits the cumulative power spectral density of acquired Schottky spectra with the underlying distribution of synchrotron amplitudes. The result of this fit is then used to reconstruct the bunch profile using the derived model. The results obtained are verified by a comparison with measurements from the LHC Wall Current Monitors.
	Slides MOCO03 [48.066 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOCO03
About •	paper received ※ 04 September 2019 paper accepted ※ 08 September 2019 issue date ※ 10 November 2019
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WECO03	Tune Computation via Model Fitting to Swept Machine Response Measurement	490
	M.G. Abbott, G. Rehm DLS, Oxfordshire, United Kingdom
	At Diamond Light Source we compute the horizontal and vertical tunes by fitting a simple multi-pole resonator model to the measured electron beam frequency response. The transverse (and longitudinal) tune response is measured by sweeping an excitation across the range of possible tune frequencies and synchronously measuring the IQ response. The multi-pole resonator model is a good fit to the measured behaviour, but the fitting process is surprisingly challenging. Problems include noisy measurements, very complex beam responses in the presence of increasing chromaticity, poor data when the beam is close to instability, and a number of challenges with the stability of the algorithm. The tune fitting algorithm now in use at Diamond has been developed and refined over many years. It is finally stable enough to work reliably throughout most beam operating conditions. The algorithm involves alternating peak finding and non-linear fitting, with a fairly naive mathematical approach; the main focus is on providing reliable results.
	Slides WECO03 [1.059 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WECO03
About •	paper received ※ 04 September 2019 paper accepted ※ 09 September 2019 issue date ※ 10 November 2019
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WECO04	Commissioning of the Non-invasive Profile Monitors for the ESS LEBT	495
	C.A. Thomas, J. Etxeberria, S. Haghtalab, H. Kocevar, N. Milas, R. Miyamoto, T.J. Shea, R. Tarkeshian ESS, Lund, Sweden
	In the Low Energy Beam Transport (LEBT) of the European Spallation Source (ESS) Linac, a specific Non-invasive Profile Monitor (NPM) has been designed to primarily monitor beam position monitor with 100 µm accuracy, and in addition enable beam profile and size measurement. We present the first measurement results using NPM during the commissioning of the LEBT. The measurement results conclude the beam position as well as the angle of the beam. The performance of the measurement is discussed and compared to the required accuracy for the position measurement. In addition, the profile of the beam along the propagation axis is reported, as measured for part or the full pulse transported in the LEBT. The fidelity of the reported profile will be discussed as function of the system sensitivity and image signal to noise ratio.
	Slides WECO04 [11.779 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WECO04
About •	paper received ※ 04 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019
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WEPP028	Laser Compton Backscattering Source for Beam Diagnostics at the S-DALINAC	582
	M.G. Meier, M. Arnold, J. Enders, N. Pietralla, M. Roth TU Darmstadt, Darmstadt, Germany V. Bagnoud GSI, Darmstadt, Germany
	Funding: Supported in part through the state of Hesse (LOEWE research cluster Nuclear Photonics) and DFG through GRK 2128 ’AccelencE’. The Superconducting DArmstadt electron LINear ACcelerator S-DALINAC is a thrice-recirculating linac* providing electron beams with energies up to 130 MeV and beam currents up to 20 ¿A for a variety of nuclear physics experiments. It has been operated as Germany¿s first energy-recovery linac (ERL) in 2017. The electron beam is produced either in a thermionic gun or a DC photo-gun using GaAs as cathode material**. A new project foresees to use the S-DALINAC for Laser Compton Backscattering (LCB) to produce a monochromatic high-energy photon beam for nuclear photonics applications in photonuclear reactions and atomics physics experiments. Besides this LCB will be used as an additional diagnostic tool for determining electron beam energy and the energy spread at the third recirculation of the S-DALINAC, when the maximum reachable energy at this point (98.8 MeV) yields a scattered photon energy of 179.7 keV. An overview over the desired laser system for LCB at the S-DALINAC will be given, and simulations for the layout and the estimated output of the Compton-backscattering light source will be presented. M. Arnold, Diss., TU Darmstadt (2017) N. Pietralla, Nucl. Phys. News 28(2), 4(2018) M. Arnold et al., Proc. IPAC¿18(4859), 9(2018) ***Y. Poltoratska et al., J.Phys.: Conf. S. 298, 012002(2011)
	Poster WEPP028 [0.900 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP028
About •	paper received ※ 04 September 2019 paper accepted ※ 11 September 2019 issue date ※ 10 November 2019
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WEPP029	Virtual Pepper-Pot Technique for 4D Phase Space Measurements	586
	G.Z. Georgiev, M. Krasilnikov DESY Zeuthen, Zeuthen, Germany
	A novel method for 4-dimensional transverse beam phase space measurement is proposed at the Photo Injector Test facility at DESY in Zeuthen (PITZ) for ongoing beam coupling studies. This method is called Virtual Pepper-Pot (VPP), because key principles of the pepper-pot mask scheme are applied. The latter approach is of limited use in high-brightness photo injectors, because of technical reasons. At PITZ a slit scan method instead is the standard tool for reconstruction of horizontal and vertical phase spaces. The VPP method extends the slit scan technique with a special post-processing. The 4D transverse phase space is reconstructed from a pepper-pot like pattern that is generated by crossing each measured horizontal slit beamlet with all measured vertical slit beamlets. All elements of the 4D transverse beam matrix are calculated and applied to obtain the 4D transverse emittance, 4D kinematic beam invariant and coupling factors. The proposed technique has been applied to experimental data from the PITZ photo injector optimization for 0.5 nC bunch charge. Details of the VPP technique and results of its application will be discussed.
	Poster WEPP029 [2.982 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP029
About •	paper received ※ 03 September 2019 paper accepted ※ 09 September 2019 issue date ※ 10 November 2019
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WEPP030	Betatron Phase Advance Measurements Using the Gated Turn-by-turn Monitors at SuperKEKB	591
	G. Mitsuka, K. Mori, M. Tobiyama KEK, Ibaraki, Japan
	In the SuperKEKB commissioning Phases 2 (Feb.-Jul., 2018) and 3 (from Mar. 2019), the betatron phase advances between adjacent beam position monitors have been measured using a total of 138 gated turn-by-turn monitors. A fast RF gating of the monitors enables turn-by-turn beam position detections by focusing only on an artificially-excited non-colliding bunch, while leaving colliding bunches unaffected. Betatron phase advances measured by the gated turn-by-turn monitors and accordingly obtained betatron functions were consistent with the closed orbit measurements. High signal-to-noise ratio were achieved by advanced signal extraction methods such as NAFF, SVD, and independent component analysis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP030
About •	paper received ※ 03 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019
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WEPP031	Long Beam Pulse Extraction by the Laser Charge Exchange Method Using the 3-MeV Linac in J-Parc	595
	H. Takei, K. Hirano, S.I. Meigo JAEA/J-PARC, Tokai-mura, Japan K. Tsutsumi Nippon Advanced Technology Co., Ltd., Tokai, Japan
	The Accelerator-driven System (ADS) is one of the candidates for transmuting long-lived nuclides, such as minor actinide (MA), produced by nuclear reactors. For efficient transmutation of the MA, a precise pre-diction of neutronics of ADS is required. In order to obtain the neutronics data for the ADS, the Japan Pro-ton Accelerator Research Complex (J-PARC) has a plan to build the Transmutation Physics Experimental Facility (TEF-P), in which a 400-MeV negative proton (H⁻) beam will be delivered from the J-PARC linac. Since the TEF-P requires a stable proton beam with a power of less than 10 W, a stable and meticulous beam extraction method is required to extract a small amount of the proton beam from the high power beam of 250 kW. To fulfil this requirement, the Laser Charge Exchange (LCE) method has been developed. To demonstrate the long beam pulse extraction using the bright continuous laser beam with a power of 196 W, we installed the LCE device at the end of a 3-MeV linac. As a result of the experiment, a charge-exchanged proton beam with a power of 0.67 W equivalent was obtained under the J-PARC linac beam condition, and this value agreed well with the theoretical value.
	Poster WEPP031 [7.256 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP031
About •	paper received ※ 04 September 2019 paper accepted ※ 09 September 2019 issue date ※ 10 November 2019
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WEPP032	Beam Based Alignment of Elements and Source at the ESS Low Energy Beam Transport Line	600
	N. Milas, M. Eshraqi, B. Gålander, Y. Levinsen, R. Miyamoto, E. Nilsson, D.C. Plostinar ESS, Lund, Sweden
	The European Spallation Source (ESS), currently under construction in Lund, Sweden, will be the world’s most powerful linear accelerator driving a neutron spallation source, with an average power of 5 MW at 2.0 GeV. The first protons were accelerated at the ESS site during the commissioning of the ion source and low energy beam transport (LEBT), that started in September 2018 and ran until July 2019. Misalignments of the elements in the LEBT can have a strong impact on the final current transmission of the low energy part. In this paper, we present a way to isolate and measure tilts of the elements and the initial centroid divergence of the source. We also present initial test measurements for the ESS LEBT and discuss how to extend the method to other facilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP032
About •	paper received ※ 04 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019
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WEPP033	Position Based Phase Scan	605
	N. Milas, M. Eshraqi, Y. Levinsen, R. Miyamoto, D.C. Plostinar ESS, Lund, Sweden Y. Liu KEK/JAEA, Ibaraki-Ken, Japan
	Knowledge of the longitudinal beam parameters is important for understanding beam dynamics in linacs. As well as with transverse optics, the settings for the RF cavities have to be established and phase and amplitude seen by the beam must be determined in order to guarantee a stable motion in the longitudinal plane. This work presents an extension of the most widely used phase scan method, relying on time-of-flight, using only transverse positions measured at a few selected BPMs downstream of the cavity being scanned. In principle, the method can be applied both to normal conducting and SC. The suggested method is fast and relatively simple and is capable to provide the values for the cavity transverse misalignment (offsets and tilts) at the same time. It can be a useful part of the initial longitudinal beam tuning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP033
About •	paper received ※ 04 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019
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WEPP034	Optics-Measurement-Based BPM Calibration	610
	A. García-Tabarés Valdivieso, R. Tomás CERN, Geneva, Switzerland
	Beam position monitors (BPMs) are key elements in accelerator operation, providing essential information about different beam parameters that are directly related to the accelerator performance. In order to obtain an accurate conversion from an induced voltage to the center of charge position, the BPMs have to be calibrated prior to its installation in the accelerator. This calibration procedure can only be performed when the accelerator is in a period of non-activity and does not completely reproduce the exact conditions that occur during the machine operation. Discrepancies observed during the optics measurements at the Large Hadron Collider and the Proton Synchrotron Booster show that the impact of the BPM calibration factors on the optics functions was greater than expected from the design values and tolerances. Measurement of the optics functions allows obtaining extra information on BPM calibration together with its associated uncertainty and resolution. The optics measurement based calibration allows further developing new techniques for computing optics functions that are biased by a possible miss-calibration such as beta function, dispersion function and beam action.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP034
About •	paper received ※ 04 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019
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WEPP035	Using Tune Measurement Systems Based on Diode Detectors for Quadrupolar Beam Oscillation Analysis in the Frequency Domain	615
	M. Gąsior, T.E. Levens CERN, Geneva, Switzerland
	Requirements for diagnostics of injection matching and beam space charge effects have driven studies at CERN using high sensitivity tune measurement systems based on diode detectors for the observation of quadrupolar beam oscillations in the frequency domain. This has led to an extension of such tune systems to include a channel optimised for quadrupolar oscillation measurements. This paper presents the principles of such measurements, the developed hardware and example measurements.
	Poster WEPP035 [29.814 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP035
About •	paper received ※ 03 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019
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WEPP036	Application of Thermoelectric Oscillations in a Lithium Niobate Single Crystal for Particle Generation	620
	K.V. Fedorov, P. Karataev JAI, Egham, Surrey, United Kingdom K.V. Fedorov TPU, Tomsk, Russia O.O. Ivashchuk, A.A. Klenin, A.S. Kubankin, A.N. Oleinik BelSU, Belgorod, Russia A.V. Shchagin NSC/KIPT, Kharkov, Ukraine
	Single crystals of lithium niobate (LiNbO3) and lithium tantalate (LiTaO3) can be used to accelerate electrons and positive ions to energies of the order of 100 keV and generate X-rays and fast neutrons, as well as to control beams of charged particles. However, this way of particles acceleration and generation is not widely used yet due to an unstable particle flux caused by electric breakdowns or crystal impurities leading to temporal discontinuity of pyroelectric current. A sinusoidal mode of the temperature change demonstrated stable oscillations of the pyroelectric current on the polar surface with typical frequency being of the order of 1-50 mHz and the amplitude being about 1-10 nA for samples with area of several cm². In vacuum it leads to generation of high electric field, which oscillates with the same frequency. Estimated amplitude of electric field is order of 105 V/cm. The possibilities of using such mode of temperature change to obtain a quasi-stable X-ray and electron source are considered. The fundamental properties and further prospects for the application of thermoelectric oscillations are also discussed.
	Poster WEPP036 [1.256 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP036
About •	paper received ※ 03 September 2019 paper accepted ※ 11 September 2019 issue date ※ 10 November 2019
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WEPP037	First Measurements of Cherenkov-Diffraction Radiation at Diamond Light Source	624
	D.M. Harryman, P. Karataev JAI, Egham, Surrey, United Kingdom M. Apollonio, L. Bobb DLS, Oxfordshire, United Kingdom M. Bergamaschi, R. Kieffer, M. Krupa, T. Lefèvre, S. Mazzoni CERN, Geneva, Switzerland A. Potylitsyn TPU, Tomsk, Russia
	Cherenkov Diffraction Radiation (ChDR), appearing when a charged particle moves in the vicinity of a dielectric medium with speed faster than the speed of light inside the medium, is a phenomenon that can be exploited for a range of non-invasive beam diagnostics. By using dielectric radiators that emit photons when in proximity to charged particle beams, one can design devices to measure beam properties such as position, direction and size. The Booster To Storage-ring (BTS) test stand at Diamond Light Source provides a 3 GeV electron beam for diagnostics research. A new vessel string has been installed to allow the BTS test stand to be used to study ChDR diagnostics applicable for both hadron and electron accelerators. This paper will discuss the commissioning of the BTS test stand, as well as exploring the initial results obtained from the ChDR monitor.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP037
About •	paper received ※ 04 September 2019 paper accepted ※ 09 September 2019 issue date ※ 10 November 2019
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WEPP038	Observation of Microbunching Instabilities using THz Detector at NSLS-II	629
	W.X. Cheng ANL, Lemont, Illinois, USA B. Bacha, G.L. Carr BNL, Upton, New York, USA
	Microbunching instabilities have been observed in several light sources with high single bunch current stored. The instability is typically associated with threshold beam currents. Energy spread and bunch length are increasing above the thresholds. Recently, a terahertz (THz) detector was installed at the cell 22 infrared (IR) beamline at NSLS-II storage ring to study the micro-bunch instabilities. The IR beamline has wide aperture allowing long-wavelength synchrotron radiation or microwave signal propagate to the end station, where the detector was installed. The detector output signal has been analyzed using oscilloscope, spectrum analyzer and FFT real-time spectrum analyzer. Clear sidebands appear as single bunch current increases and the sidebands tend to shift/jump. We present measurement results of the THz detector at different nominal bunch lengths and ID gaps.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP038
About •	paper received ※ 04 September 2019 paper accepted ※ 08 September 2019 issue date ※ 10 November 2019
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WEPP039	Single-Shot Diagnostics of Microbunched Electrons in Laser-Driven Plasma Accelerators and Free-Electron Lasers	633
	A.H. Lumpkin Fermilab, Batavia, Illinois, USA D.W. Rule Private Address, Silver Spring, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The need for single-shot diagnostics of the periodic longitudinal density modulation of relativistic electrons at the resonant wavelength (microbunching) in a free-electron laser (FEL) or at broadband visible wavelengths as in a laser-driven plasma accelerator (LPA) has been reaffirmed. In the self-amplified spontaneous emission (SASE) FEL case, statistical fluctuations in the microbunching occur in the startup-from-noise process. In the LPA, the plasma itself is chaotic and varies shot to shot. Fortunately, we have shown that coherent optical transition radiation (COTR) techniques, can assess beam size, divergence, spectral evolution, and z-dependent gain (100, 000) of microbunched electrons in a past SASE FEL experiment at 530 nm. Recently, the application to LPAs has been demonstrated with single-shot near-field (NF) and far-field (FF) COTR imaging done at the exit of an LPA for the first time. In this case few-micron beam sizes and extensive fringes due to sub-mrad divergences were measured based on point-spread-function effects and an analytical model for COTR interferometry, respectively. A proposed diagnostics application at 266 nm to pre-bunched beams is also described. A.H. Lumpkin et al., Phys. Rev. Lett. 88, No.23, 234801 (2002). **A.H. Lumpkin, M. LaBerge, D.W. Rule, et al., Proceedings of AAC18, (IEEE), 2019.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP039
About •	paper received ※ 10 September 2019 paper accepted ※ 11 September 2019 issue date ※ 10 November 2019
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WEPP040	Optimization of Antiproton Capture for Antihydrogen Creation in the ALPHA Experiment	637
	S.S. Fabbri, W. Bertsche UMAN, Manchester, United Kingdom
	At the ALPHA Experiment at CERN, thin foils of material are used to slow down and trap antiprotons in a Penning trap, where they can be used for antihydrogen creation and measurements. Historically, over 99% of antiprotons are lost during the capture process as a result of the 5.3 MeV initial kinetic energy of the beam delivered by the Antiproton Decelerator. This places a limit early on in the achievable number of antihydrogen. ELENA is a new storage ring coming online which will lower this initial kinetic energy of the beam to 100 keV, requiring experiments to update their infrastructure. We present Monte Carlo and particle tracking simulation results for the optimization of the new degrading foil material, thickness, and location in the ALPHA catching Penning trap. From these results, we expect an upper capture efficiency of roughly 50 %. We further propose techniques for manipulating, detecting and extracting on the anticipated larger-numbered antiproton plasmas. These methods and associated hardware developments will allow performing antiproton experiments with significantly higher efficiency in ALPHA and other similar antiproton-based experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP040
About •	paper received ※ 04 September 2019 paper accepted ※ 11 September 2019 issue date ※ 10 November 2019
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WEPP042	Measurement of the Second Moments of Transverse Beam Distribution with Solenoid Scan	642
	I. Pinayev BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Measurement of the dependence of the beam size on profile monitor vs. strength of a focusing element is widely used for measurement of the beam parameters. Such measurements are mostly used for the separate planes and assumption that beam satisfied Gaussian distribution. In many linear accelerators the transverse beam dynamics is coupled between planes and distribution is far from the Gaussian. We developed measurement technique of the second moments of beam distribution which does not rely on any assumptions. The theory and experimental results are presented.
	Poster WEPP042 [1.756 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP042
About •	paper received ※ 03 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019
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WEPP043	Time-of-flight Technique for Matching Energies in Electron Cooler	645
	I. Pinayev, R.L. Hulsart, K. Mernick, R.J. Michnoff, Z. Sorrell BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Electron cooler with bunched electron beam is being commissioned at the Relativistic Heavy Ion Collider at BNL. For the cooler to operate the energies of the hadron and electron beams should be matched with high accuracy. We have developed time-of-flight technique based on the phase measurement of the beam induced signal in the beam position monitors separated by a drift. We present the method description and experimental results.
	Poster WEPP043 [9.892 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP043
About •	paper received ※ 03 September 2019 paper accepted ※ 09 September 2019 issue date ※ 10 November 2019
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THAO01	Cherenkov Diffraction Radiation as a tool for beam diagnostics	660
	T. Lefèvre, D. Alves, M. Bergamaschi, A. Curcio, O.R. Jones, R. Kieffer, S. Mazzoni, N. Mounet, A. Schlogelhofer, E. Senes CERN, Meyrin, Switzerland M. Apollonio, L. Bobb DLS, Oxfordshire, United Kingdom A. Aryshev, N. Terunuma KEK, Ibaraki, Japan M.G. Billing, Y.L. Bordlemay Padilla, J.V. Conway, J.P. Shanks Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA V.V. Bleko, S.Yu. Gogolev, A.S. Konkov, J.S. Markova, A. Potylitsyn, D.A. Shkitov TPU, Tomsk, Russia K.V. Fedorov, D.M. Harryman, P. Karataev, K. Lekomtsev JAI, Egham, Surrey, United Kingdom J. Gardelle CEA, LE BARP cedex, France K. Łasocha Jagiellonian University, Kraków, Poland
	During the last three years, the emission of Cherenkov Diffraction Radiation (ChDR), appearing when a relativistic charged particle moves in the vicinity of a dielectric medium, has been investigated with the aim of providing non-invasive beam diagnostics. ChDR has very interesting properties, with a large number of photons emitted in a narrow and well-defined solid angle, providing excellent conditions for detection with very little background. This contribution will present a collection of recent beam measurements performed at several facilities such as the Cornell Electron Storage Ring, the Advanced Test Facility 2 at KEK, the Diamond light source in the UK and the CLEAR test facility at CERN. Those results, complemented with simulations, suggest that the use of both incoherent and coherent emission of Cherenkov diffraction radiation could open up new beam instrumentation possibilities for relativistic charged particle beams.
	Slides THAO01 [10.658 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-THAO01
About •	paper received ※ 09 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019
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Paper

Title

Page

Estimation of Longitudinal Profiles of Ion Bunches in the LHC Using Schottky-Based Diagnostics

45

K. Łasocha, D. Alves
CERN, Meyrin, Switzerland

The Large Hadron Collider (LHC) Schottky monitors have been designed to measure various parameters of relevance to beam quality, namely tune, momentum spread and chromaticity. We present another application of this instrument - the evaluation of longitudinal bunch profiles. The relation between the distribution of synchrotron amplitudes within the bunch population and the longitudinal bunch profile is derived from probabilistic principles. Our approach, limited to bunched beams with no intra-bunch coherent motion, initially fits the cumulative power spectral density of acquired Schottky spectra with the underlying distribution of synchrotron amplitudes. The result of this fit is then used to reconstruct the bunch profile using the derived model. The results obtained are verified by a comparison with measurements from the LHC Wall Current Monitors.

Slides MOCO03 [48.066 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOCO03

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paper received ※ 04 September 2019 paper accepted ※ 08 September 2019 issue date ※ 10 November 2019

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WECO03

Tune Computation via Model Fitting to Swept Machine Response Measurement

490

M.G. Abbott, G. Rehm
DLS, Oxfordshire, United Kingdom

At Diamond Light Source we compute the horizontal and vertical tunes by fitting a simple multi-pole resonator model to the measured electron beam frequency response. The transverse (and longitudinal) tune response is measured by sweeping an excitation across the range of possible tune frequencies and synchronously measuring the IQ response. The multi-pole resonator model is a good fit to the measured behaviour, but the fitting process is surprisingly challenging. Problems include noisy measurements, very complex beam responses in the presence of increasing chromaticity, poor data when the beam is close to instability, and a number of challenges with the stability of the algorithm. The tune fitting algorithm now in use at Diamond has been developed and refined over many years. It is finally stable enough to work reliably throughout most beam operating conditions. The algorithm involves alternating peak finding and non-linear fitting, with a fairly naive mathematical approach; the main focus is on providing reliable results.

Slides WECO03 [1.059 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WECO03

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paper received ※ 04 September 2019 paper accepted ※ 09 September 2019 issue date ※ 10 November 2019

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WECO04

Commissioning of the Non-invasive Profile Monitors for the ESS LEBT

495

C.A. Thomas, J. Etxeberria, S. Haghtalab, H. Kocevar, N. Milas, R. Miyamoto, T.J. Shea, R. Tarkeshian
ESS, Lund, Sweden

In the Low Energy Beam Transport (LEBT) of the European Spallation Source (ESS) Linac, a specific Non-invasive Profile Monitor (NPM) has been designed to primarily monitor beam position monitor with 100 µm accuracy, and in addition enable beam profile and size measurement. We present the first measurement results using NPM during the commissioning of the LEBT. The measurement results conclude the beam position as well as the angle of the beam. The performance of the measurement is discussed and compared to the required accuracy for the position measurement. In addition, the profile of the beam along the propagation axis is reported, as measured for part or the full pulse transported in the LEBT. The fidelity of the reported profile will be discussed as function of the system sensitivity and image signal to noise ratio.

Slides WECO04 [11.779 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WECO04

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paper received ※ 04 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019

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WEPP028

Laser Compton Backscattering Source for Beam Diagnostics at the S-DALINAC

582

M.G. Meier, M. Arnold, J. Enders, N. Pietralla, M. Roth
TU Darmstadt, Darmstadt, Germany
V. Bagnoud
GSI, Darmstadt, Germany

Funding: Supported in part through the state of Hesse (LOEWE research cluster Nuclear Photonics) and DFG through GRK 2128 ’AccelencE’.
The Superconducting DArmstadt electron LINear ACcelerator S-DALINAC is a thrice-recirculating linac* providing electron beams with energies up to 130 MeV and beam currents up to 20 ¿A for a variety of nuclear physics experiments**. It has been operated as Germany¿s first energy-recovery linac (ERL) in 2017***. The electron beam is produced either in a thermionic gun or a DC photo-gun using GaAs as cathode material****. A new project foresees to use the S-DALINAC for Laser Compton Backscattering (LCB) to produce a monochromatic high-energy photon beam for nuclear photonics applications in photonuclear reactions and atomics physics experiments. Besides this LCB will be used as an additional diagnostic tool for determining electron beam energy and the energy spread at the third recirculation of the S-DALINAC, when the maximum reachable energy at this point (98.8 MeV) yields a scattered photon energy of 179.7 keV. An overview over the desired laser system for LCB at the S-DALINAC will be given, and simulations for the layout and the estimated output of the Compton-backscattering light source will be presented.
*M. Arnold, Diss., TU Darmstadt (2017)
**N. Pietralla, Nucl. Phys. News 28(2), 4(2018)
***M. Arnold et al., Proc. IPAC¿18(4859), 9(2018)
****Y. Poltoratska et al., J.Phys.: Conf. S. 298, 012002(2011)

Poster WEPP028 [0.900 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP028

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paper received ※ 04 September 2019 paper accepted ※ 11 September 2019 issue date ※ 10 November 2019

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WEPP029

Virtual Pepper-Pot Technique for 4D Phase Space Measurements

586

G.Z. Georgiev, M. Krasilnikov
DESY Zeuthen, Zeuthen, Germany

A novel method for 4-dimensional transverse beam phase space measurement is proposed at the Photo Injector Test facility at DESY in Zeuthen (PITZ) for ongoing beam coupling studies. This method is called Virtual Pepper-Pot (VPP), because key principles of the pepper-pot mask scheme are applied. The latter approach is of limited use in high-brightness photo injectors, because of technical reasons. At PITZ a slit scan method instead is the standard tool for reconstruction of horizontal and vertical phase spaces. The VPP method extends the slit scan technique with a special post-processing. The 4D transverse phase space is reconstructed from a pepper-pot like pattern that is generated by crossing each measured horizontal slit beamlet with all measured vertical slit beamlets. All elements of the 4D transverse beam matrix are calculated and applied to obtain the 4D transverse emittance, 4D kinematic beam invariant and coupling factors. The proposed technique has been applied to experimental data from the PITZ photo injector optimization for 0.5 nC bunch charge. Details of the VPP technique and results of its application will be discussed.

Poster WEPP029 [2.982 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP029

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paper received ※ 03 September 2019 paper accepted ※ 09 September 2019 issue date ※ 10 November 2019

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WEPP030

Betatron Phase Advance Measurements Using the Gated Turn-by-turn Monitors at SuperKEKB

591

G. Mitsuka, K. Mori, M. Tobiyama
KEK, Ibaraki, Japan

In the SuperKEKB commissioning Phases 2 (Feb.-Jul., 2018) and 3 (from Mar. 2019), the betatron phase advances between adjacent beam position monitors have been measured using a total of 138 gated turn-by-turn monitors. A fast RF gating of the monitors enables turn-by-turn beam position detections by focusing only on an artificially-excited non-colliding bunch, while leaving colliding bunches unaffected. Betatron phase advances measured by the gated turn-by-turn monitors and accordingly obtained betatron functions were consistent with the closed orbit measurements. High signal-to-noise ratio were achieved by advanced signal extraction methods such as NAFF, SVD, and independent component analysis.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP030

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paper received ※ 03 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019

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WEPP031

Long Beam Pulse Extraction by the Laser Charge Exchange Method Using the 3-MeV Linac in J-Parc

595

H. Takei, K. Hirano, S.I. Meigo
JAEA/J-PARC, Tokai-mura, Japan
K. Tsutsumi
Nippon Advanced Technology Co., Ltd., Tokai, Japan

The Accelerator-driven System (ADS) is one of the candidates for transmuting long-lived nuclides, such as minor actinide (MA), produced by nuclear reactors. For efficient transmutation of the MA, a precise pre-diction of neutronics of ADS is required. In order to obtain the neutronics data for the ADS, the Japan Pro-ton Accelerator Research Complex (J-PARC) has a plan to build the Transmutation Physics Experimental Facility (TEF-P), in which a 400-MeV negative proton (H⁻) beam will be delivered from the J-PARC linac. Since the TEF-P requires a stable proton beam with a power of less than 10 W, a stable and meticulous beam extraction method is required to extract a small amount of the proton beam from the high power beam of 250 kW. To fulfil this requirement, the Laser Charge Exchange (LCE) method has been developed. To demonstrate the long beam pulse extraction using the bright continuous laser beam with a power of 196 W, we installed the LCE device at the end of a 3-MeV linac. As a result of the experiment, a charge-exchanged proton beam with a power of 0.67 W equivalent was obtained under the J-PARC linac beam condition, and this value agreed well with the theoretical value.

Poster WEPP031 [7.256 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP031

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paper received ※ 04 September 2019 paper accepted ※ 09 September 2019 issue date ※ 10 November 2019

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WEPP032

Beam Based Alignment of Elements and Source at the ESS Low Energy Beam Transport Line

600

N. Milas, M. Eshraqi, B. Gålander, Y. Levinsen, R. Miyamoto, E. Nilsson, D.C. Plostinar
ESS, Lund, Sweden

The European Spallation Source (ESS), currently under construction in Lund, Sweden, will be the world’s most powerful linear accelerator driving a neutron spallation source, with an average power of 5 MW at 2.0 GeV. The first protons were accelerated at the ESS site during the commissioning of the ion source and low energy beam transport (LEBT), that started in September 2018 and ran until July 2019. Misalignments of the elements in the LEBT can have a strong impact on the final current transmission of the low energy part. In this paper, we present a way to isolate and measure tilts of the elements and the initial centroid divergence of the source. We also present initial test measurements for the ESS LEBT and discuss how to extend the method to other facilities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP032

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paper received ※ 04 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019

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WEPP033

Position Based Phase Scan

605

N. Milas, M. Eshraqi, Y. Levinsen, R. Miyamoto, D.C. Plostinar
ESS, Lund, Sweden
Y. Liu
KEK/JAEA, Ibaraki-Ken, Japan

Knowledge of the longitudinal beam parameters is important for understanding beam dynamics in linacs. As well as with transverse optics, the settings for the RF cavities have to be established and phase and amplitude seen by the beam must be determined in order to guarantee a stable motion in the longitudinal plane. This work presents an extension of the most widely used phase scan method, relying on time-of-flight, using only transverse positions measured at a few selected BPMs downstream of the cavity being scanned. In principle, the method can be applied both to normal conducting and SC. The suggested method is fast and relatively simple and is capable to provide the values for the cavity transverse misalignment (offsets and tilts) at the same time. It can be a useful part of the initial longitudinal beam tuning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP033

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paper received ※ 04 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019

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WEPP034

Optics-Measurement-Based BPM Calibration

610

A. García-Tabarés Valdivieso, R. Tomás
CERN, Geneva, Switzerland

Beam position monitors (BPMs) are key elements in accelerator operation, providing essential information about different beam parameters that are directly related to the accelerator performance. In order to obtain an accurate conversion from an induced voltage to the center of charge position, the BPMs have to be calibrated prior to its installation in the accelerator. This calibration procedure can only be performed when the accelerator is in a period of non-activity and does not completely reproduce the exact conditions that occur during the machine operation. Discrepancies observed during the optics measurements at the Large Hadron Collider and the Proton Synchrotron Booster show that the impact of the BPM calibration factors on the optics functions was greater than expected from the design values and tolerances. Measurement of the optics functions allows obtaining extra information on BPM calibration together with its associated uncertainty and resolution. The optics measurement based calibration allows further developing new techniques for computing optics functions that are biased by a possible miss-calibration such as beta function, dispersion function and beam action.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP034

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paper received ※ 04 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019

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WEPP035

Using Tune Measurement Systems Based on Diode Detectors for Quadrupolar Beam Oscillation Analysis in the Frequency Domain

615

M. Gąsior, T.E. Levens
CERN, Geneva, Switzerland

Requirements for diagnostics of injection matching and beam space charge effects have driven studies at CERN using high sensitivity tune measurement systems based on diode detectors for the observation of quadrupolar beam oscillations in the frequency domain. This has led to an extension of such tune systems to include a channel optimised for quadrupolar oscillation measurements. This paper presents the principles of such measurements, the developed hardware and example measurements.

Poster WEPP035 [29.814 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP035

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paper received ※ 03 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019

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WEPP036

Application of Thermoelectric Oscillations in a Lithium Niobate Single Crystal for Particle Generation

620

K.V. Fedorov, P. Karataev
JAI, Egham, Surrey, United Kingdom
K.V. Fedorov
TPU, Tomsk, Russia
O.O. Ivashchuk, A.A. Klenin, A.S. Kubankin, A.N. Oleinik
BelSU, Belgorod, Russia
A.V. Shchagin
NSC/KIPT, Kharkov, Ukraine

Single crystals of lithium niobate (LiNbO3) and lithium tantalate (LiTaO3) can be used to accelerate electrons and positive ions to energies of the order of 100 keV and generate X-rays and fast neutrons, as well as to control beams of charged particles. However, this way of particles acceleration and generation is not widely used yet due to an unstable particle flux caused by electric breakdowns or crystal impurities leading to temporal discontinuity of pyroelectric current. A sinusoidal mode of the temperature change demonstrated stable oscillations of the pyroelectric current on the polar surface with typical frequency being of the order of 1-50 mHz and the amplitude being about 1-10 nA for samples with area of several cm². In vacuum it leads to generation of high electric field, which oscillates with the same frequency. Estimated amplitude of electric field is order of 105 V/cm. The possibilities of using such mode of temperature change to obtain a quasi-stable X-ray and electron source are considered. The fundamental properties and further prospects for the application of thermoelectric oscillations are also discussed.

Poster WEPP036 [1.256 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP036

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paper received ※ 03 September 2019 paper accepted ※ 11 September 2019 issue date ※ 10 November 2019

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WEPP037

First Measurements of Cherenkov-Diffraction Radiation at Diamond Light Source

624

D.M. Harryman, P. Karataev
JAI, Egham, Surrey, United Kingdom
M. Apollonio, L. Bobb
DLS, Oxfordshire, United Kingdom
M. Bergamaschi, R. Kieffer, M. Krupa, T. Lefèvre, S. Mazzoni
CERN, Geneva, Switzerland
A. Potylitsyn
TPU, Tomsk, Russia

Cherenkov Diffraction Radiation (ChDR), appearing when a charged particle moves in the vicinity of a dielectric medium with speed faster than the speed of light inside the medium, is a phenomenon that can be exploited for a range of non-invasive beam diagnostics. By using dielectric radiators that emit photons when in proximity to charged particle beams, one can design devices to measure beam properties such as position, direction and size. The Booster To Storage-ring (BTS) test stand at Diamond Light Source provides a 3 GeV electron beam for diagnostics research. A new vessel string has been installed to allow the BTS test stand to be used to study ChDR diagnostics applicable for both hadron and electron accelerators. This paper will discuss the commissioning of the BTS test stand, as well as exploring the initial results obtained from the ChDR monitor.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP037

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paper received ※ 04 September 2019 paper accepted ※ 09 September 2019 issue date ※ 10 November 2019

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WEPP038

Observation of Microbunching Instabilities using THz Detector at NSLS-II

629

W.X. Cheng
ANL, Lemont, Illinois, USA
B. Bacha, G.L. Carr
BNL, Upton, New York, USA

Microbunching instabilities have been observed in several light sources with high single bunch current stored. The instability is typically associated with threshold beam currents. Energy spread and bunch length are increasing above the thresholds. Recently, a terahertz (THz) detector was installed at the cell 22 infrared (IR) beamline at NSLS-II storage ring to study the micro-bunch instabilities. The IR beamline has wide aperture allowing long-wavelength synchrotron radiation or microwave signal propagate to the end station, where the detector was installed. The detector output signal has been analyzed using oscilloscope, spectrum analyzer and FFT real-time spectrum analyzer. Clear sidebands appear as single bunch current increases and the sidebands tend to shift/jump. We present measurement results of the THz detector at different nominal bunch lengths and ID gaps.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP038

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paper received ※ 04 September 2019 paper accepted ※ 08 September 2019 issue date ※ 10 November 2019

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WEPP039

Single-Shot Diagnostics of Microbunched Electrons in Laser-Driven Plasma Accelerators and Free-Electron Lasers

633

A.H. Lumpkin
Fermilab, Batavia, Illinois, USA
D.W. Rule
Private Address, Silver Spring, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The need for single-shot diagnostics of the periodic longitudinal density modulation of relativistic electrons at the resonant wavelength (microbunching) in a free-electron laser (FEL) or at broadband visible wavelengths as in a laser-driven plasma accelerator (LPA) has been reaffirmed. In the self-amplified spontaneous emission (SASE) FEL case, statistical fluctuations in the microbunching occur in the startup-from-noise process. In the LPA, the plasma itself is chaotic and varies shot to shot. Fortunately, we have shown that coherent optical transition radiation (COTR) techniques, can assess beam size, divergence, spectral evolution, and z-dependent gain (100, 000) of microbunched electrons in a past SASE FEL experiment at 530 nm*. Recently, the application to LPAs has been demonstrated with single-shot near-field (NF) and far-field (FF) COTR imaging done at the exit of an LPA for the first time**. In this case few-micron beam sizes and extensive fringes due to sub-mrad divergences were measured based on point-spread-function effects and an analytical model for COTR interferometry, respectively. A proposed diagnostics application at 266 nm to pre-bunched beams is also described.
*A.H. Lumpkin et al., Phys. Rev. Lett. 88, No.23, 234801 (2002).
**A.H. Lumpkin, M. LaBerge, D.W. Rule, et al., Proceedings of AAC18, (IEEE), 2019.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP039

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paper received ※ 10 September 2019 paper accepted ※ 11 September 2019 issue date ※ 10 November 2019

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WEPP040

Optimization of Antiproton Capture for Antihydrogen Creation in the ALPHA Experiment

637

S.S. Fabbri, W. Bertsche
UMAN, Manchester, United Kingdom

At the ALPHA Experiment at CERN, thin foils of material are used to slow down and trap antiprotons in a Penning trap, where they can be used for antihydrogen creation and measurements. Historically, over 99% of antiprotons are lost during the capture process as a result of the 5.3 MeV initial kinetic energy of the beam delivered by the Antiproton Decelerator. This places a limit early on in the achievable number of antihydrogen. ELENA is a new storage ring coming online which will lower this initial kinetic energy of the beam to 100 keV, requiring experiments to update their infrastructure. We present Monte Carlo and particle tracking simulation results for the optimization of the new degrading foil material, thickness, and location in the ALPHA catching Penning trap. From these results, we expect an upper capture efficiency of roughly 50 %. We further propose techniques for manipulating, detecting and extracting on the anticipated larger-numbered antiproton plasmas. These methods and associated hardware developments will allow performing antiproton experiments with significantly higher efficiency in ALPHA and other similar antiproton-based experiments.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP040

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paper received ※ 04 September 2019 paper accepted ※ 11 September 2019 issue date ※ 10 November 2019

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WEPP042

Measurement of the Second Moments of Transverse Beam Distribution with Solenoid Scan

642

I. Pinayev
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Measurement of the dependence of the beam size on profile monitor vs. strength of a focusing element is widely used for measurement of the beam parameters. Such measurements are mostly used for the separate planes and assumption that beam satisfied Gaussian distribution. In many linear accelerators the transverse beam dynamics is coupled between planes and distribution is far from the Gaussian. We developed measurement technique of the second moments of beam distribution which does not rely on any assumptions. The theory and experimental results are presented.

Poster WEPP042 [1.756 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP042

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paper received ※ 03 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019

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WEPP043

Time-of-flight Technique for Matching Energies in Electron Cooler

645

I. Pinayev, R.L. Hulsart, K. Mernick, R.J. Michnoff, Z. Sorrell
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron cooler with bunched electron beam is being commissioned at the Relativistic Heavy Ion Collider at BNL. For the cooler to operate the energies of the hadron and electron beams should be matched with high accuracy. We have developed time-of-flight technique based on the phase measurement of the beam induced signal in the beam position monitors separated by a drift. We present the method description and experimental results.

Poster WEPP043 [9.892 MB]

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paper received ※ 03 September 2019 paper accepted ※ 09 September 2019 issue date ※ 10 November 2019

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THAO01

Cherenkov Diffraction Radiation as a tool for beam diagnostics

660

T. Lefèvre, D. Alves, M. Bergamaschi, A. Curcio, O.R. Jones, R. Kieffer, S. Mazzoni, N. Mounet, A. Schlogelhofer, E. Senes
CERN, Meyrin, Switzerland
M. Apollonio, L. Bobb
DLS, Oxfordshire, United Kingdom
A. Aryshev, N. Terunuma
KEK, Ibaraki, Japan
M.G. Billing, Y.L. Bordlemay Padilla, J.V. Conway, J.P. Shanks
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
V.V. Bleko, S.Yu. Gogolev, A.S. Konkov, J.S. Markova, A. Potylitsyn, D.A. Shkitov
TPU, Tomsk, Russia
K.V. Fedorov, D.M. Harryman, P. Karataev, K. Lekomtsev
JAI, Egham, Surrey, United Kingdom
J. Gardelle
CEA, LE BARP cedex, France
K. Łasocha
Jagiellonian University, Kraków, Poland

During the last three years, the emission of Cherenkov Diffraction Radiation (ChDR), appearing when a relativistic charged particle moves in the vicinity of a dielectric medium, has been investigated with the aim of providing non-invasive beam diagnostics. ChDR has very interesting properties, with a large number of photons emitted in a narrow and well-defined solid angle, providing excellent conditions for detection with very little background. This contribution will present a collection of recent beam measurements performed at several facilities such as the Cornell Electron Storage Ring, the Advanced Test Facility 2 at KEK, the Diamond light source in the UK and the CLEAR test facility at CERN. Those results, complemented with simulations, suggest that the use of both incoherent and coherent emission of Cherenkov diffraction radiation could open up new beam instrumentation possibilities for relativistic charged particle beams.

Slides THAO01 [10.658 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-THAO01

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paper received ※ 09 September 2019 paper accepted ※ 10 September 2019 issue date ※ 10 November 2019

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